Previously there is known from WO 2006/016007 A1 a solution where individual frames of input data are divided into blocks, and each such block is compared to a corresponding block of a prediction frame in order to identify changed blocks and unchanged blocks. The blocks identified as unchanged are modified by setting the colour values of the pixels of these blocks to a predetermined value, and a signal is generated to contain all the blocks including the changed blocks and the unchanged blocks. The colour value of the unchanged movement blocks has been selected such that a codec encoding the generated signal works as efficiently as possible.
Once the original frames need to be regenerated, the encoded signal is decoded, and a prediction frame is modified for each subsequent frame such that only the changed blocks of the decoded signal are used for modifying the prediction frame, while the unchanged blocks of the decoded signal whose pixel values correspond to the predetermined colour value are not used for modifying the prediction frame.
The above described prior art solution works efficiently for video images. However, it would be desirable to still reduce the amount of data that needs to be transmitted or stored between the processing of the original frames and the regeneration of the original frames.